Riffle trough



Sept. 24, 1935. A. o. HOFFMAN RIFFLE THOUGH Filed D60. 16, 1951 NI N\ \x 0 O O o 0 0 O O Q 0 MW. NN m NM Raw 0M K T E F MM W mHWM 0- A D E RW u H Patented Sept. 24, 1935- UNITED STATES A'E'ENT OFFICE 9 Claims.

The invention relates to improvements in the construction of riffle troughs wherein pulverized or finely divided solid material containing particles of the heavier precious metals is arranged 6 to be conveyed in a stream of water flowing across a series of rifiles for gravity settlement of the metal particles into collecting pockets of the riflie structure An -object of the invention is to provide a riflle assembly of knock-down structure for permitting a replacement or substitution of riflle elements in the assembly thereof, said elements of general channel section.

Another object is to provide rifiie pockets of improved section for insuring the segregation and retention of metal particles therein.

A further object is to provide for using side elements of the trough for defining and sealing the ends of the riffle pockets, said side elements separable from the riflie elements for permitting the aforesaid replacement or substitution of the latter elements.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth or be apparent in the following description of a typical embodiment of the invention which is illustrated in the accompanying drawing, in which,

Figure 1 is a perspective side view of a rifile trough embodying the invention, a side element of the trough being shown fragmentarily and in displaced position.

Figure 2 is a sectional elevation through the trough when in condition for use, said section taken generally at the line 2-2 in Figure 1.

Figure 3 is a fragmentary full face view of a portion of the riflie structure of Figure 1, flow lines of the material passing thereover being indicated in the view.

Figure 4 is a fragmentary perspective view disclosing the interlocking engagement of rifiie members of the structure.

As particularly illustrated, the features of the present invention are incorporated in the structure of a rifiie trough comprising opposite side walls 5 and 6 having a series of rifiies extending between them. A receiving apron l is provided at the upstream end of the riflie portion of the trough, said apron arranged to receive a waterborne and pulverized mixture containing metal particles for separation in the riffle pockets. By way of illustration, a trough spout 8 is fragmentarily shown as disposed (Figure 1) above the apron l for delivering the aforesaid mixture thereto. At the lower, or downstream, end of the rifiies, a discharge apron 9 is provided for receiving the material from which the metal'particles have been separated in the riille pockets.

The trough sides 5 and 6 extend upwardly from the sides H of a shallow box l2 of uniform 5 width, said box providing a base for the rifile trough. The trough sides 5 and 6 preferably compose metal plates and are provided at their upper ends with inturned longitudinal flanges l3 disposed somewhat above the level of the 10 riffies. The flanges l3 are designed to minimize loss of material from the trough by splashing, may be used for supporting a grizzly or other accessory across the trough, and are understood to stiffen the side plates against bending or flexl5 ure longitudinally of thetrough.

The riifles, it will now be noted, comprise a unitary assembly which provides a series of grooves extending transversely of the'trough and terminating at the trough sides 5 and 6. Preferably, and as shown, said grooves terminate in common planes at the opposite sides of the rilfle assembly whereby the latter may abut the inner faces of the trough sides Sand 6 in said planes to form pockets of said grooves.

Means are provided for sealing the ends of the rifile grooves at the trough sides 5 and 6, and said means preferably comprise the provision of relatively soft facing elements M on the sides 5 and 6 and in opposition to the planar sides of the riffle' assembly. As particularlyindicated, the facing elements M are of wood; it is tobe understood however, that the same might be of other material such as fabric, rubber or cork compositions, etc. In this manner a pre'ssure'eng'agement of the trough sides with the riflle sides is arranged to more or less embed the ends of the riffle grooves thereat whereby leakless pockets are defined along the riffle assembly. In the present instance, the receiving and discharge 40 aprons 1 and 9 respectively are of the same Width as the riffie assembly whereby they may also be sealedly engaged between the facing elements M of the trough sides.

While the riflieassembly constitutes a unit with 5 respect to its sealing between the trough sides 5 and B, it is preferred to form said assembly of a plurality of independently formed rifile members of generalchannel form, said members being similar as to certain features thereof, and dissimilar 5,0? as to other features. As particularly illustrated,

the first four riifle grooves at the upstream end of the riflle assembly are provided'in like riffle members l5, six like rifile members I6 follow the members 15, and asingle riffie member ILcompletes the rifile assembly. Grooves, or pockets, l8, l9 and 20 are respectively provided in the rifile members l5, l3 and I1, said grooves being of different shapes at the bottom portions thereof. It Will be understood that the number, order, and form of riflle members used in the assembly would vary with the nature of the material to be handled and with other factors of operation, and that the particular arrangement shown is merely illustrative of one possible assembly of the riilie members.

Referring now more particularly to the structure of the rifiie members, it is to be noted that each of these members is formed of suitable sheet material, and that means are provided for directly interlocking the upper edges of opposed side walls of the adjacent members whereby said members cooperate to solely provide the trough bottom at the riffie assembly. By reference to the form of the members It, it is noted that each said member is provided with an upstream wall portion 2| and a downstream wall portion 22, said wall portions being mutually parallel and generally perpendicular to the longitudinal axis of the trough. At the top of each wall 22, an integral apron portion 23 extends obliquely downwardly in'a downstream direction, and a further and integral edge portion 24 is formed to provide an upwardly opening channel beneath the portion 23. The free edge of the portion 24 is spaced from the apron 23 and from the downstream face of the wall 22 by a distance which is no less than the thickness of the material used to form the member IS; in this manner, a space 25 is defined between the apron portion 23 and edge portion 24 and the top part of the wall 22. A downwardly turned and integral flange 26 is provided at the top of each wall 2|, said flange shaped for engagement beneath an apron portion 23 and in the space 25 whereby adjacent members 56 may be engaged and locked together against lateral separation thereof.

With the described interlocking means for the members IE, it will be clear that a flange 26 of a given member l6 must be inserted from an end of the space 25 of the adjacent member 16 for effecting the assembly shown. The present assembly is seen to dispose the apron portions 23 in general enclosing relation to the flanges 26 and at the upstream edges of the rifiie pockets, whereby leakage at the joints is minimized. It will now be noted that the downstream edges of the receiving apron 1 and of the riflie members I? and I are also formed to define the spaces 25 at the downstream sides thereof. Flanges 26 are provided at the upstream sides of the members i! and I5 and of the discharge apron 9 for insertion in appropriate spaces 25 of the different members. In this manner, the various members !5, l6 and I! may be associated in any desired order or number with and between the receiving and discharge aprons l and 9 to provide a unitary bottom assembly for a rifile trough, said assembly being secured by and between the side elements 5 and 6 in the previously described manner.

The side plate 5, it will now be noted, is longitudinally divided to define upper and lower portions 21 and 28 thereof. The lower plate portion 28 is fixed along a side of the base box l2 and the upper portion 21 is hinged to the portion 28 whereby the latter portion may be swung to and from its operative position against a side of the described rifile assembly; the swinging portion 2! is respectively shown in inoperative and operative positions in Figures 1 and 2. By reason of the displaceability of the plate 27, the placement or rearrangement of the riffie assembly is arranged to be facilitated.

With the. side plates 5 and 5 both engaging 5 opposed sides of the described rifile and apron assembly, bolts 23 are engaged with and between the plates at spaced points therealong whereby a turning up of nuts 3! on the bolts may compress the said assembly between the relatively soft facing elements It for embedding the assembly sides in said elements to provide the desired degree of seal; as shown in Figures 1 and 2, more or less permanent grooves 32 are formed in the elements 14 as the result of the engagement of the elements with the riflle and apron members of the trough bottom assembly. Preferably, and as shown, the bolts 29 define a single plane extending lonigtudinally of the trough and generally centrally through the riflle assembly whereby the elements M are drawn against the sides of said assembly with uniform pressure. It will now be particularly noted that the sealing elements M are spaced from the bottom of the plates 5 and 6 whereby to permit any necessary bending of these plates longitudinally therealong and laterally of the trough; in this manner, a proper application of the sealing elements is assured. If desired, cleats 33 may be provided along the inner sides of the plates 5 and 6 for supporting the trough bottom assembly during the mounting thereof between the plates.

Referring now to the specific form of the riflle members IE, it is noted that the bottom of each said member comprises a planar and integral portion 34 extending obliquely downwardly from the bottom edge of its downstream wall 22 to a point on the upstream side of the plane of its wall ill. The wall 2i extends slightly lower than the wall 22 and a flat bottom portion 35 extends obliquely from the bottom edge thereof. The lower edges of the bottom portions 34 and 35 are integrally connected by a cylindrically curved portion 35 to complete the groove 19. Preferably, and as shown, the bottom portion 34 and 5 the apron 23 at the bottom and top respectively of the wall 22, each make forty-five degree angles with the plane of said wall. As brought out in Figure 3, the spacing of the walls 2| and 22 is such that when a series of members 56 are interlocked in the described manner, the plane of the apron 23 of one member will inmrsect the opposite wall 22 of the succeeding member substantially at'the bottom of said wall and where the portion at joins it.

With the section of the groove 5 9 as shown and now described, the swirl produced in said groove as the water and ore mixture flows down the trough wi l centrifugally throw the heavier, and metallic, particles against the face of the bottom portion 34 for gravity settlement along said wall to the bottom of the pocket, it being obvious that the heaviest said particles will ultimately reach the bottom of the groove. Preferably, and as shown, certain of the rifiie pockets may contain quicksilver 6! for amalgamation with gold or silver particles of the material being treated. Platinum particles are designed to be caught and retained solely by reason of their weight. In those rifiie members it which are designed to receive the quicksilver, a valved outlet 42 pipe is provided for gravity discharge into a manifold pipe 23; in this manner, the unamalgamated quicksilver may be drawn off before the amalgamated mass is removed from the grooves I9.

The rilile member II, it is noted, differs only from the member E6 in having a somewhat wider groove and a correspondingly altered bottom portion. This member is designed primarily to trap any quicksilver or amalgam which may have been carried from the members I6 with the gangu'e. The bottom of the member I! is also connected with the manifold pipe 43.

The rifiie members 15 comprise upper walls 44 and 45 at the upstream and downstream sides thereof. A planar bottom wall 46 extends obliquely downwardly from the bottom edge of each wall 44, the latter said wall being of the same depth as the walls 22 of the members and the wall 45 defining the same angle with the wall 44 as that defined by the wall 34 with the wall 22 of the member IS. The planar wall 45 extends to a juncture with the wall 46 tocomplete the definition of the groove H3. The memhere !5, it is noted, function to segregate and retain the larger particles of the precious metal to be saved, and the action at the walls 46 corresponds to that at the bottom portions 34 of the members it.

The unitary rifile trough structure now described, it is noted, may be suitably supported in an inclinedposition to provide a desired gradient for the flow of the material being treated; as particularly shown, blocks 5| and 52 support the structure in an inclined position. The described structure may, of course, be supported on a vibrating platform, or otherwise shaken, if such is desired. The base box l2, it is noted, may function to retain any liquid escaping from the rifile assembly, a perforated plate 53 extending thereacross at its lower end for limiting the height to which the liquid may accumulate in the box.

From the foregoing description taken in connection with the accompanying drawing, the advantages of the construction and method of operation will be readily understood by those skilled in the art to which the invention appertains, and while I have described the principle of operation, together with the device which I now consider to be the best embodiment thereof, I desire to have it understood that the device shown is merely illustrative, and that such changes may be made, when desired, as fall within the scope of the appended claims.

Having thus described my invention, I claim as new and desire to secure by Letters Patent of the United States the following:

1. In a riffie trough, a riffie structure comprising a bottom portion formed of sheet metal to provide collecting grooves extending transversely of the trough, longitudinal side members of the trough engaging said bottom portion at the ends of said grooves and presenting faces of yielding material thereagainst, tension rods cooperative between said side members to clamp said bottom portion between them for embedding the side edges of the bottom portion in said faces to seal the groove ends, a supporting base beneath said trough and in spaced relation therefrom, and plates of resilient material extending upwardly from said base and directly carrying said side members.

2. In a riflie trough, a riflle structure comprising a bottom portion formed of sheet metal to provide collecting grooves extending transversely of the trough, longitudinal side members of the trough engaging said bottom portion at the ends of said grooves and presenting faces of yielding material thereagainst, tension rods disposed in a common plane extending longitudinally and centrally of said bottom portion and cooperative between said side members toclamp the bottom portion between them for embedding the side edges of the bottom portion in said facesto seal the groove ends, a supporting base beneath said trough and in spaced relation therefrom, and plates of resilient material extending upwardly from said base and directly carrying said side members, one of said plates hinged to said base.

3. In a riflie trough, a rifile structure providing a succession of grooves extending transversely in the trough bottom, forward andrear sides of said grooves planar and substantially perpendicular to the longitudinal trough axis, and corresponding bottom portions of said grooves planar and ex- 5 tending obliquely downwardly and rearwardly from the bottoms of the forward groove sides.

4. In a rifile trough, a riiile structure providing a succession of grooves extending transversely in the trough bottom, forward and rear sides of said grooves planar and substantially perpendicular to the longitudinal trough axis, and corresponding bottom portions of said grooves planar and ex' tending obliquely downwardly and rearwardly from the bottoms of the forward groove sides, said 25 bottom portions making substantially forty-five degree angles with said forward groove sides.

5. In a, riflle trough, a riiile structure providing a succession of grooves extending transversely in the trough bottom, forward and rear sides of said grooves planar and substantially perpendicular to the longitudinal trough axis, and corresponding bottom portions of said grooves planar and extending obliquely downwardly and rearwardly from the bottoms of the forward groove sides, and aprons provided at the tops, of said groove sides and providing planar faces sloping downwardly and forwardly to define substantially forty-five degree angles with said groove sides.

6. In a riffle trough, a riflle structure providing a succession of grooves extending transversely in the trough bottom, forward and rear sides of said grooves planar and substantially perpendicular to the longitudinal trough axis, and corresponding bottom portions of said grooves planar andextending obliquely downwardly and rearwardly from the bottoms of the forward groove sides, said bottom portions making substantially fortyfive degree angles with said forward groove sides, and aprons provided at the tops of said groove sides and providing planar faces sloping downwardly and forwardly to define substantially forty-five degree angles with said groove sides, the planes of said apron faces intersecting the opposite wall of said grooves substantially at the bottoms of said forward groove sides.

7. In an hydraulic riffie trough, a rifile structure providing a groove in the trough bottom extending thereacross, mutually opposed forward and rear side portions of said groove planar, bottom .portions of said groove planar and extending forward groove side to a juncture with the rearward groove side at the bottom of the latter.

9. In an hydraulic rifile trough, adjacent onepiece channel elements shaped of sheet metal and disposed transversely of and defining the trough bottom thereat, the upper part of the downstream wall of a said element shaped to provide a top edge for the wall and an apron portion sloping downwardly from said edge in a downstream direction and a channel portion beneath said apron opening upwardly and spaced from the wall, and

the upperpart of the upstream wall of the element adjacent and at the downstream side of the first element shaped to provide a top edge for the wall and a depending portion spaced from the wall at its downstream side and arranged for engagement in the said channel portion of the first element whereby said walls are mutually interlocked against mutual separation transversely of the plane of the trough bottom.

ALFRED O. HOFFMAN. 

